The marking of mediums reflects the content of the medium and allows the dissemination of information wherein the end user can identify the subject matter located within the medium. In addition, logos, trademarks, text, graphics, and bar codes can be added to the medium for marketing, sales and cataloging of information.
The printing processes for printing information and graphics on the surface of a medium including plastic disks or compact disks, generally include a silk screening printing process, a printer utilizing ink jet printing technology, a labeling process or a thermal printing process. However, in any printing process, it is desirable that the pressure against the medium be uniformly applied during the printing process in order to insure the highest quality of printing onto the medium.
One of the most popular types of media is optical disks, such as compact disks and digital video disks, or digital versatile disks. The optical disk or CD has recently become a popular form of media for storing digital information, recording high quality audio and video information and also for recording computer software of various types. With advances in technology, it is now possible not only to read information from such optical media, but also to record digital information directly onto the media. For example, recordable compact disks (referred to as CD-Rs) may have digital information recorded on them by placing the CD-R into a compact disk recorder that receives the digital information from a computer. Such forms of optical media are thus particularly useful for data distribution and/or archiving.
Compact disks are standardized in two sizes and configurations, one having an overall diameter of 4.72 inches, a central hole of 0.59 inches, and a central region about the center hole of 1.50 inches in diameter, wherein no information is either printed or recorded, The other standard disk size is 3.5 inches in overall diameter, with a comparable central hole size and central region. In the case of disks for utilization in connection with computer processors, the recording formats and content are typically adapted to the particular generalized type of computer processor with which the disk is to operate. Some compact disks are recorded in such a way as to be usable with several different computer processor types, i.e., PC, Macintosh, etc.
The significant increases in use of CD disks and CD-R disks as a data distribution vehicle has increased the need to provide customized CD label content to reflect the data content of the disk. Initially, the customized label information was “hand written” on the disk surface using felt tipped markers. While this approach permitted users to individually identify disks, it tends to be labor intensive, prone to human error in transcription, and aesthetically limited.
Other attempts to provide a CD or CD-R labeling solution have incorporated digitally printed adhesive labels. Precut labels are printed using desktop or commercial ink-jet, thermal wax transfer, or printers. An example of such labels is the STOMP Company's (Irvine, Calif.) CD Stomper package of die-cut CD labels that can be printed on any 8.5 by 11 inch ink jet or laser electrophotographic printer. Following printing, the labels can be applied manually with or without the aid of an alignment tool or a specially designed machine. This method can be labor intensive, and the CD-R can be damaged if the label is removed. In addition, system performance problems can occur due to disk imbalance or label de-lamination in the CD writer or reader.
Within the past several years, however, methods for direct CD labeling have been growing in prominence. These methods utilize the versatility and ease of the setup associated with digital printing to provide customized label content directly on a disk surface. The most commonly used direct CD printers incorporate ink jet or thermal wax transfer technologies. These printers can be either stand alone or integrated into a computerized disk writing system reducing problems associated with labor, human error, disk damage, and imbalance.
CDs are often coated with a printable surface opposite to the surface from which the information is recorded and retrieved. On the printable surface, a label is printed which can be logos, trademarks, text, graphics, and bar codes, etc., which are related to the information stored on the CD. The label also protects the CD from physical damage. Because the CD spins at high speed in the writer and the player, the CD label needs to be precisely balanced to the center of the disk for smooth rotation.
Labeling of CD disks has routinely been accomplished through screen printing methods. While this method can provide a wide variety of label content, it tends to be cost ineffective for run lengths less than 300-400 disks because the fixed cost on unique materials and set-up are shared by all the disks in each run. The screen printing technique is well described in the textbook “Graphic Arts Manual”, edited by Janet and Irving Field, Arno/Musarts Press, New York, N.Y., 1980, pp. 416 to 418. In screen printing a stencil of the image is prepared, placed in contact with the CD and then ink is spread by squeegee across the stencil surface. Where there are openings in the stencil the ink passes through to the surface of the CD, thus producing the image. Preparation of the stencil is an elaborate, time consuming and expensive process.
Accordingly, what is desired is an in-line marking system having a marking device which can mark indicia on a large number of mediums including compact disks in an efficient and expedient manner.